SAN FRANCISCO – Treating a coronary artery with both a drug-eluting balloon and a bare metal stent is feasible in patients with acute ST-elevation myocardial infarction but does not significantly reduce late lumen loss, compared with bare metals stents alone or with drug-eluting stents alone.
The Drug-Eluting Balloon in Acute Myocardial Infarction (DEB-AMI) trial failed to meet its primary end point of a 50% reduction in late lumen loss at 6 months with the combination, Dr. Pieter R. Stella reported at Transcatheter Cardiovascular Therapeutics 2011. There was also no advantage for the combination in terms of clinical outcomes.
The drug-eluting balloon and bare metal stent combination "induces some morphological changes that are seen with [optical coherence tomography] and acetylcholine testing, but this is insufficient to result in superior angiographic results," he said in a press conference. "The drug-eluting stent is better in all comparisons."
However, he added, more detailed analyses suggested that results with the combination may have been influenced by procedural factors and differences across centers and operators.
"The use of the drug-eluting balloon probably needs special dedication by the operator," Dr. Stella maintained. "Further investigation is needed to optimize the results; we think that predilatation is extremely important with a drug-eluting balloon."
The trial took a futuristic approach to STEMI treatment, according to Dr. Juan F. Granada, executive director and chief scientific officer at the Jack H. Skirball Center for Cardiovascular Research, New York.
Much is unknown about the use of drug-eluting balloons in this context, he explained. "We really don’t know what is the drug uptake, especially with high doses delivered in the setting of ruptured plaque and thrombotic burden, and the pharmacokinetic profile in their presence, and the potential for toxicity that exists, especially when you combine drug elution with a bare metal stent."
He said it was "very interesting" to see that results for the combination were between those of a bare metal stent alone and the drug-eluting stent alone.
"So even though I applaud the hypothesis and investigators’ initiative, I think this was a bold approach to do the trial, knowing the pharmacokinetic profiles of drug-eluting balloons," Dr. Granada said.
Explaining the trial’s rationale, Dr. Stella noted that bare metal stents are safe but have high restenosis rates. And drug-eluting stents carry the potential risks of malapposition to the vessel wall and uncovered struts, which could increase the risk of late stent thrombosis.
Thus, hypothetically, there might be advantages to combined use of a drug-eluting balloon and bare metal stents: The combination might permit local drug delivery just to the vulnerable plaque; allow brief exposure of the vessel to an antiproliferative drug, leading to better healing of the endothelium; cause less restenosis than bare metal stents alone; cause less late (acquired) malapposition of the stent, compared with a drug-eluting stent; and preserve endothelial function.
To be eligible for the trial, sponsored by UMC Utrecht, patients had to first undergo successful thrombus aspiration. They were then randomized in balanced fashion to treatment with bare metal stents alone (Magic, manufactured by EuroCor), the combination of a drug-eluting balloon (Dior, manufactured by EuroCor) and bare metal stents (Magic), or drug-eluting stents alone (Taxus Liberté, manufactured by Boston Scientific).
For the sake of comparability, the drug-eluting balloon and drug-eluting stents both delivered paclitaxel, Dr. Stella, an interventional cardiologist at the University Medical Centre Utrecht (the Netherlands), said at the meeting sponsored by the Cardiovascular Research Foundation.
The patients were reevaluated clinically and angiographically with quantitative coronary analysis at 6 months. About one-fourth also underwent optical coherence tomography (OCT) with acetylcholine endothelial testing at that time.
Results for 127 patients showed that the angiographic late lumen loss at 6 months, the trial’s primary end point, averaged 0.78 mm in the group treated with bare metal stents alone, 0.64 mm in the group treated with the drug-eluting balloon and bare metal stent combination (a nonsignificant reduction), and 0.21 mm in the group treated with drug-eluting stents.
Dr. Stella pointed out that although predilatation was mandated in all three groups, it was done in only 60% of cases in the combination group and within that group, the rate of late lumen loss was indeed greater when the vessel was predilated (0.49 vs. 0.85 mm, P = .04).
"We found out that experienced [drug-eluting balloon] operators had better results than nonexperienced operators," he also noted, with a smaller late lumen loss seen for the principal investigator than for the operators overall.
The bare metal stent and balloon plus bare metal stent groups had similar rates of clinical outcomes such as major adverse cardiovascular events (24% and 20%) and target lesion revascularization (18% and 20%). By comparison, the drug-eluting stent group had dramatically lower rates of major adverse cardiovascular events (4%) and target lesion revascularization (2%).